The present invention relates to a process for the production of a braking band for a brake disk with venting passages, and a braking band produced by the process.
In particular, the present invention relates to a process for the production of a braking band which has venting passages and is made of a ceramic material such as, for example C/SiC.
In general, braking bands with venting passages which are currently available on the market are produced by two different processes.
The first process provides for the moulding of the braking band as a solid body and for the subsequent formation of radial and non-radial holes lying in a central plane of the thickness of the band and thus constituting the venting passages.
The second process provides for a first step for the moulding of two reflectively symmetrical portions of the braking band having grooves in their facing surfaces. The two portions are then brought into contact and glued to form the finished product in which each groove of each of the portions represents one half of a venting duct.
However, the above-mentioned solutions have some disadvantages.
In the first process, the formation of the holes in the thickness of the braking bands is undoubtedly very difficult because of the hardness of the materials which have to be used in production.
The second process, on the other hand, has the great disadvantage that it is necessary to glue two portions of a braking band which, since they are formed separately, may not correspond and may therefore fit together incorrectly. This could give rise to a product which might easily be subject to dangerous detachment of these two portions.
As a result, there is a need to provide a process for the production of braking bands with venting passages which is particularly easy to implement and effective, as well as braking bands produced by the process.
The problem upon which the present invention is based is therefore to devise a process for the production of braking bands which has characteristics such as to satisfy the above-mentioned requirements and at the same time to overcome the disadvantages of the processes of the prior art.
This problem is solved by a process for the production of a braking band having venting passages, comprising the following steps:
moulding a core of the braking band in a suitable mould,
moulding two covers onto the core in a further suitable mould so as to form a semi-finished product having a xe2x80x9csandwichxe2x80x9d structure,
firing the semi-finished product so as to produce a predetermined porosity of the covers,
firing the semi-finished product further, in the presence of silicon, at a temperature such as substantially to bring about fusion of the silicon and its infiltration into the covers.
Further characteristics and the advantages of the process for the production of braking bands, as well as the braking bands produced by the process according to the present invention, will become clear from the following description of some preferred embodiments thereof, given by way of non-limiting example with reference to the appended drawings.